“Don’t worry when you go on,” Tommy Corcoran told John Stewart Service as he was about to enter the grand jury room. “This is double riveted from top to bottom.” By “double riveted” Corcoran meant the deal was sealed in every which way.

When the DOJ’s inspector general, Michael Horowitz, releases his report on the Hillary Clinton email scandal, presumably on Thursday, the nation will have its first real sense of whether this investigation is “double riveted” as well.

For those wanting to know what a double riveted spy case smells like, there is no better source than M. Stanton Evans’s indispensable 2007 book on Sen. Joe McCarthy and his era, “Blacklisted by History.”

This first act in John Service’s own drama played out in 1945. Service, a foreign service officer in the employ of the State Department, had been arrested on espionage charges for passing confidential documents about China to his friends at a flagrantly pro-communist magazine called Amerasia.

The FBI had Service dead to rights. J. Edgar Hoover called the case against him “air tight.” At the time, however, Hoover was struggling against a deep state far deeper than the one Donald Trump confronts today.

In control of all branches of government for the previous 12 years, Democrats had allowed, in some cases encouraged, communists and their active sympathizers to root deeply into every relevant branch of the federal apparatus, State and Treasury most consequentially.

Tommy “the Cork” Corcoran, had served for years as FDR’s fixer-in-residence. In the Service case, he proved to be as good as his word. The grand jury cleared Service on a 20-0 vote, which was proof enough for the media and many historians of Service’s innocence.

Unbeknownst to Corcoran at the time of his “double riveted” comment, the new president, Harry Truman, had had the FBI wiretap his phones. He did so largely out of spite. Corcoran had opposed Truman’s nomination as vice-president in 1944.

This is how honest historians like Evans know about Corcoran’s mischief. The dishonest ones, and they are legion, prefer to think of Service and his cronies as victims of Republican witch hunters.

Although he has a reputation as something of a cold warrior, Truman’s sweeping secrecy orders in 1948 protected Service and scores of other federal officials from further investigation.

A haberdasher at heart, Truman was more worried about the brand than about the bigger picture. Thanks largely to the subversive work of Service and other “China hands,” some actual communist agents, China fell, but the Democratic brand endured.

With criminal cases fixed and secrets safely buried, the Democrats regained control of the House and Senate in the 1948 elections, and Truman was elected president. After a short period of unease, the deep state had reinserted its control over Washington.

Or so the deep-staters thought. In February 1950, the little known Senate back bencher Joe McCarthy boldly disrupted the status quo, declaring that there were at least 57 known communists still burrowed in the Washingtonian swamp, John Service among them.

By this time, the Reds had taken over China, the Russians had the bomb, and North Korean generals were making plans. Seemingly fearless and shockingly well-informed, McCarthy threw the deep state into a panic.

Within days of his introductory speech in Wheeling, West Virginia, Democrats and their media allies had launched a vicious counter-attack on McCarthy himself.

In 1950, the media were not the monolith they are today. McCarthy had some influential newspaper support. In the first two years of his campaign, he rallied public opinion behind him.

Truman Secretary of State Dean Acheson fired Service and several other security risks, and security screening was tightened throughout government. In no small part due to McCarthy’s revelations, Republicans recaptured the Senate and the White House in the 1952 election.

This is when McCarthy’s troubles really began. As long as McCarthy confined his investigation to the Truman administration, the Republicans in Congress backed him.

When McCarthy turned his sights on the U.S. Army’s Signal Corps at Fort Monmouth in New Jersey, he got a glimpse of just how deep the deep state could be.

Those now aligned against McCarthy, wrote Evans, included “two presidents of the United States, vast bureaucratic empires, formidable adversaries in Congress, relentless leftward lobby groups, and a horde of press, TV, and radio critics who made him their daily target.”

Protective of the Army brand, President Dwight Eisenhower and his fixers thwarted McCarthy at every turn. Many Senate Republicans, McCarthy learned, worried more about currying favor with the new president than about rooting communists out of government.

The Democrats in the Senate hated McCarthy with a passion that would go unmatched until Donald Trump surfaced some 60 years later. They allied with their “moderate” Republican brethren to censure McCarthy for attempting to drain the swamp. In so doing, they collectively killed McCarthy’s career.

The battles lines in 2018 are eerily similar. Enraged Democrats and weak-kneed Republicans ally to block a man bold enough and rude enough to challenge the deep state head on.

McCarthy got double riveted into oblivion, but Trump has two huge advantages over McCarthy. One is the Oval Office. The other is the internet.

It remains to be seen how this will all play out. Cynics are betting on the swamp, but smart money favors Trump. The FBI will prove to be his ally too. Stay tuned.